Project Summary: Texas Children's Hospital aims to establish and operate a year round surveillance site as part of a larger national New Vaccine Surveillance Network (NVSN) to better understand the burden of vaccine-preventable disease, the impact of new vaccine and the impact of changing vaccine policies. To understand the disease burden of rotavirus or other vaccine-preventable diseases, the surveillance team at Texas Children's Hospital proposes to enroll children with symptoms of acute gastroenteritis in both emergency and inpatient settings during all grant years. As the Texas Children's Hospital emergency department treats >82,000 children per year from a multi-county area who are demographically similar to the children in the greater Houston area, the hospital is well suited to conduct such surveillance activities. Fecal specimens will be collected from all enrolled children at the time of enrollment or by courier. All fecal specimens will be tested using Rotaclone enzyme immunoassay. Children whose fecal specimens test positive for rotavirus antigen, case patients, will then be compared with healthy patients who present to the Texas Children's Pediatric Associates for well-child care, control patients. Complete vaccination histories will be collected from case and control patients. Vaccine effectiveness for rotavirus, and possibly other vaccine-preventable diseases, will be determined. Additionally, saliva specimens will be collected from a subset of case and healthy children for assessment of FUT2 secretor antigen status. During grant years 2-5, we propose to collaborate with the CDC to assist in the development and implementation of additional projects. These projects may include, but would not be limited to the following: extension of surveillance activities to other vaccine-preventable diseases, evaluation of uptake and impact of new vaccines on provider policies and practice habits, longitudinal studies involving a cohort of children following new vaccine introduction, laboratory studies involving the development of new research methods, and health care costs studies associated with vaccine policy.